It is known, in particular from French patent specification No. 2 745 075, to provide a heat exchanger of the above type which comprises a packet or stack of fins made in the form of thin metallic leaves of rectangular form, which extend parallel to each other through which the tubes of the bundle pass. Each of the side faces, or minor faces, is protected by the lateral traverse member or side cover, which protects the free edges of the fins, these edges being particularly fragile. In this type of known heat exchanger, the spine portion of the side cover is deformable and has a concave form so as to take up clearance between the side cover and the matrix (having regard to the dimensional variations which are inherent in high quantity production).
Due to the concavity of the spine portion of the side cover, the two side branches of the latter have a natural tendency to spread apart from each other, which gives rise to a danger that the anchor hooks may become inadvertently disengaged from the notches in the fins of the matrix. In order to reduce this danger, it is necessary to make the anchor hooks, and the corresponding notches, with specific shapes which are similar to those of a fish hook or harpoon.
In addition, in the known heat exchangers of the above type, it frequently happens that at least one of the side covers includes a lateral wing portion, which may for example constitute a profiled sealing element for making sealing engagement against an appropriate item of equipment of the vehicle or against the structure of the vehicle itself. When this wing portion is subjected to a force, by engagement with such a part of the vehicle, it can increase the natural tendency of the side branches of the side cover to spread apart from each other, with consequent separation of the side cover from the matrix.